Surgical instrument for expanding body tissue

ABSTRACT

A surgical instrument for performing procedures such as carpal tunnel release. The instrument consists of an elongated member having a spring or cam plate positioned therein. The spring or cam plate is movable from a retracted position within the elongated member to an extended position protruding through an aperture in the elongated member. Movement of the spring or cam plate to the extended position stretches a flexible membrane positioned over at least a portion of the elongated member to stretch the carpal tunnel ligament.

This is a continuation of application Ser. No. 08/434,965 filed May 4,1995, now U.S. Pat. No. 5,720,763 which is a divisional of applicationSer. No. 08/124,778 filed Sep. 21, 1993, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to surgical instruments for expanding bodytissue, and more particularly to an instrument for expanding ligamentssuch as the carpal ligament in the hand during surgical procedures suchas carpal tunnel release.

2. Discussion of the Related Art

Carpal tunnel syndrome is a condition of the hand which typicallyresults in loss of feeling, weakness or numbness (paresthesia) in thefingers and hand. In general, repetitive, short stroke motion of thefingers and hand may lead to irritation of the median nerve which passesthrough the carpal tunnel, and this initation or inflammation may leadto pain, weakness of the muscles and general numbness in the fingers andhand. The carpal tunnel is an area in the hand adjacent the wrist whichis bounded by the carpal bones of the hand and the transverse carpalligament. The median nerve and flexor tendons pass through the tunnel tocontrol movement of the fingers. As the median nerve becomes irritated,or as the transverse carpal ligament is thickened due to repetitivemotions of the hand and wrist, compression of the nerve inside thecarpal tunnel leads to carpal tunnel syndrome and its associateddegenerative conditions.

In order to treat carpal tunnel syndrome, it has been known to cut ordivide the transverse carpal ligament, also known as the flexorretinaculum, to provide for decompression of the carpal tunnel.Historically, the division of the transverse carpal ligament was doneduring open surgical procedures which involved slitting the palm of thehand to expose the ligament prior to cutting the ligament. Recently,instrumentation has been developed to allow this procedure to beperformed endoscopically, with a small incision at the base of the wristto allow for division of the ligament beneath the skin. Once theligament is cut, it allows for additional space in the carpal tunnelarea to relieve the irritation and pressure on the median nerve.

Several instruments are known for performing endoscopic decompression bydivision of the transverse carpal ligament. An instrument known as thePaine retinaculotome, as described in the Journal of Neurosurgery, Vol.59, December 1983, pp. 1031-1036, provides a cutting edge which isengagable with the transverse carpal ligament on the wrist side of theligament The Paine instrument is inserted into the hand through anincision at the base of the wrist. As the ligament is engaged by thecutting instrument, the instrument is advanced forward into the hand todivide the ligament. A similar instrument is disclosed in U.S. Pat. No.5,029,573 to Chow which provides a cannula that is inserted into thehand at the base of the wrist and includes a longitudinal slot in thecannula to allow for a cutting instrument to be inserted into thecannula. The instrument may be advanced through the ligament to dividethe ligament, or may be inserted into the distal end of the cannulawhich protrudes from the palm of the patient so that the cuttinginstrument may be drawn through the ligament as the cutting instrumentextends through the slot in the cannula.

As disclosed in U.S. Pat. Nos. 4,962,770, 4,963,147 and 5,089,000 toAgee is et al., an endoscopic instrument for performing carpal tunnelrelease is provided which includes a pivotable cutting blade whichextends outside the sheath to effect cutting of the transverse carpalligament. An endoscope may be provided for viewing the surgical site. Adisadvantage of these instruments is that the blade of the cuttinginstrument is exposed in such a manner that there control of theinstrument to prevent cutting of tissues other than the transversecarpal ligament is minimal, and in effect will allow cutting of anytissue which happens to be in the way of the blade.

Furthermore, these known instruments either require the use of numerouscomponents, such as that disclosed in the Chow patent, or provideinstruments with numerous moving parts, such as that disclosed in theAgee et al. patents, which reduce the control of the instrument in theconfined area of the carpal tunnel.

Other surgical cutting instruments are known which provide for cuttingtissue by pinching the tissue between a cutting blade and a wall or stopmember of the instrument. Such an instrument is disclosed in U.S. Pat.No. 5,176,695 to Dulebohn which discloses a hook like cutting memberwhich is drawn across a gap in the end of the instrument to hook tissuesuch as blood vessels. The blood vessels are engaged in the gap againsta wall of the instrument to cut the tissue against the wall. Similarinstruments are shown in U.S. Pat. No. 3,902,498 to Niederer, U.S. Pat.No. 3,995,619 to Glatzer, and U.S. Pat. No. 4,620,547 to Boebel. Adisadvantage of these instruments lies in the fact that they can onlycut vessels or other tissues that will fit into the gap so that thetissue may be pinched between the cutting edge and the wall againstwhich the cutting edge is force.

As disclosed in U.S. Pat. No. 769,829 to Mott, a surgical instrument isprovided having a head which houses a rearwardly directed cutting bladewhich is exposed upon movement of the head away from a housing. As thehead is moved away from the housing, an opening or gap is definedbetween the head and the housing so that the blade may be drawnrearwardly to cut vessels or tissues that are positioned within the gapas the blade moves rearwardly against the housing. This instrumentsuffers the same disadvantages as the instruments described above whichpinch tissue or vessels between the cutting blade and a wall of theinstrument.

U.S. Pat. No. 5,179,963 to Berger discloses an alternative method oftreating carpal tunnel syndrome which avoids cutting the transversecarpal ligament. In this method, a balloon catheter is inserted with theaid of a director device underneath the transverse carpal ligament. Theballoon catheter is serially inflated and deflated while it is movedalong the carpal tunnel to stretch the ligament to increase the diameterof the carpal tunnel, thereby relieving compression of the median nerve.

It would be advantageous to have alternative instrumentation which canstretch the carpal tunnel ligament as well as other body structureswithout requiring an inflatable balloon. Such instrumentation shouldprovide for controllably expanding the carpal tunnel and could provideeither expansion of the entire ligament at once or expansion a portionat a time.

SUMMARY OF THE INVENTION

The present invention provides a method for expanding the carpal tunnelduring carpal tunnel surgery comprising the steps of providing aninstrument having a spring member, inserting the instrument into thecarpal tunnel by extending the spring member to extend from theinstrument to stretch the carpal tunnel ligarment, retracting the springmember and withdrawing the instrument from the carpal tunnel. The springmember can be repeatedly extended and retracted to gradually stretch theligament by actuating a handle member connected to the instrument body.The step of extending the spring member preferably simultaneouslystretches a membrane positioned on the instrument.

A method for expanding the carpal tunnel by stretching the carpalligament during carpal tunnel surgery is also provided comprising thesteps of providing an instrument having a housing portion, asubstantially rigid member and a membrane, inserting the instrument intothe carpal tunnel, and actuating the instrument to extend the rigidmember from the housing to contact and stretch the membrane to stretchthe carpal ligament. The member is then retracted toward the housing toretract the membrane and the instrument is withdrawn from the carpaltunnel. The step of actuating the instrument can comprise the step ofcamming the substantially rigid member through an aperture in theinstrument.

An apparatus for expanding the carpal tunnel ligament during carpaltunnel surgery is also provided The apparatus includes an elongated bodyportion having a longitudinal opening formed therein, a spring memberpositioned within said body and movable between a first positionsubstantially contained within said body portion and a second positionprotruding through the opening to contact and stretch the body tissue,and means for controllably moving the spring member between the firstand second positions. The apparatus further comprises a flexiblemembrane positioned over at least a portion of the elongated bodyportion. Means for moving the spring member in a first direction towardsaid second position and means for preventing extension of said springmember in a direction opposite to said first direction can also beprovided.

The present invention can also provide an apparatus for expanding thecarpal tunnel ligament during carpal tunnel surgery comprising anelongated body portion having at least one aperture formed in an outersurface with at least one substantially rigid member positioned in saidbody portion and movable between a retracted position and an extendedposition. The rigid member extends through the aperture and protrudesbeyond the outer surface when moved to the extended position. Means forcontrollably moving said rigid member between the retracted and extendedpositions is provided. The apparatus further includes a flexiblemembrane positioned over at least a portion of said elongated bodyportion and expandable upon movement of the substantially rigid memberto the extended position. The elongated body portion is preferablysubstantially circular in cross section and has a longitudinal axisdividing said body portion into first and second sections, wherein thesubstantially rigid member moves only in said first section. A plunger,longitudinally movable in said body portion, can move said substantiallyrigid member.

The apparatus for expanding body tissue may also comprise an elongatedmember having a predetermined peripheral portion, wherein thepredetermined peripheral portion defines only a segment of theperipheral portion. A first member is positioned in the elongated memberfor movement between a first retracted position and a second extendedposition to stretch body tissue and a membrane is positioned over atleast a portion of said elongated member. Means is positioned withinsaid elongated member for moving the first member from the extendedposition to the retracted position to expand the membrane, the firstmember being extended only towards the predetermined peripheral portion.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described here and below withreference to the drawings wherein:

FIG. 1 is a perspective view of a first embodiment of the presentinvention utilizing a plunger handle for deploying the membrane;

FIG. 2 is a side view of the apparatus of FIG. 1 with the plunger in theextended (undeployed) position;

FIG. 3 is a cross-sectional view of the apparatus of FIG. 2;

FIG. 3A is a cross-sectional view taken along lines 3A--3A of FIG. 3;

FIG. 4 is a cross-sectional view of the apparatus of FIG. 1 in thedeployed position;

FIG. 5 is an alternate embodiment of the handle mechanism utilizing aslide button mechanism for deploying the membrane;

FIG. 6 is another alternate embodiment of the handle mechanism, in theform of a pistol grip, for deploying the membrane;

FIG. 7 is a cross-sectional view of an alternate embodiment of theapparatus of the present invention, shown in the undeployed position;

FIG. 7A is a cross-sectional view taken along line 7A--7A of FIG. 7;

FIG. 8 is a side view of the apparatus of FIG. 7;

FIG. 9 is a cross-sectional view of the apparatus of FIG. 7 showing theplunger depressed and the instrument in the deployed position;

FIG. 10 is a cross sectional view of another alternate embodiment of theinstrument of the present invention, shown with the plunger and membranein the undeployed position;

FIG. 10A is a cross-sectional view taken along lines 10A--10A of FIG.10;

FIG. 11 is a side view of the apparatus of FIG. 10;

FIG. 12 is a cross-sectional view of the apparatus of FIG. 10 in thedeployed position;

FIG. 13 is yet another alternate embodiment of the apparatus of thepresent invention for deploying a membrane, shown in the undeployedposition;

FIG. 13A is a cross-sectional view taken along lines 13A--13A of FIG.13;

FIG. 14 is a side view of the apparatus of FIG. 13;

FIG. 15 is a cross-sectional view of the apparatus of FIG. 13 showingthe plunger and membrane in the deployed position;

FIG. 16 is still another alternate embodiment of the apparatus fordeploying a membrane in accordance with the present invention, shown inthe undeployed position;

FIG. 16A is a cross-sectional view taken along lines 16A--16A of FIG.16;

FIG. 17 is a cross-sectional view of the apparatus of FIG. 16 showingthe plunger depressed and the membrane in the deployed position;

FIG. 18 is a cross-sectional view of yet another alternate embodiment ofthe apparatus of the present invention showing the plunger in theextended position and the membrane in the undeployed position;

FIG. 18A is a cross-sectional view taken lines 18A--18A of FIG. 18;

FIG. 19 is a cross-sectional view of the apparatus of FIG. 18 showingthe membrane in the deployed (expanded) position;

FIG. 20 is a side view of another alternate embodiment of an apparatusfor deploying a membrane utilizing a slide button mechanism;

FIG. 21 is a cross-sectional view of the apparatus of FIG. 20 showingthe apparatus in the undeployed position;

FIG. 21A is a cross-sectional view taken along lines 21A--21A of FIG.21;

FIG. 22 is a cross-sectional view of the apparatus of FIG. 20 showingthe apparatus in the deployed position;

FIG. 23 is an exploded perspective view of the apparatus of FIG. 20;

FIG. 24 is a cross-sectional view of yet another alternate embodiment ofthe apparatus for deploying a membrane utilizing a slide buttonmechanism, the apparatus being shown in the undeployed position;

FIG. 24A is a cross-sectional view taken along lines 24A--24A of FIG.24;

FIG. 25 is a side view of the instrument of FIG. 24 shown in thedeployed position;

FIG. 26 is a cross-sectional view of the apparatus of FIG. 24 shown inthe deployed position;

FIG. 27 is still another alternate embodiment of the apparatus of thepresent invention utilizing a pair of jaws to stretch the body tissue,the jaws being shown in the closed position;

FIG. 28 is a side view of the instrument of FIG. 27;

FIG. 29 is a cross-sectional view of the apparatus of FIG. 28 showingthe jaws in the open position;

FIG. 30 is a cross-sectional view of yet another alternate embodiment ofan apparatus of the present invention utilizing a pair of jaws fordeploying a membrane, the jaws being shown in the closed position housedwithin the apparatus;

FIG. 31 is a side view of the apparatus of FIG. 30; and

FIG. 32 is a cross-sectional view of the apparatus of FIG. 30 showingthe jaws in the open deployed position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings, in which like reference numerals identifysimilar or identical elements, FIG. 1 illustrates a first embodiment ofthe apparatus of the present invention designated generally by referencenumeral 1. The instrument 1 includes a handle or grip portion 10, anelongated body portion 12 extending from the handle 10, and a plunger 14slidably disposed therein. A membrane 16 is disposed over the bodyportion 12. (It should be noted that for purposes of clarity, themembrane is not shown in all the Figures of each of the embodimentsdiscussed below.) The elongated body portion includes a distal portion13, a proximal portion 15 and apertures 18 and 20. As shown in FIG. 3, acam plate 24 is attached to body portion 12 by fixed pin 28. Cam plate24 also includes camming slot 27 in which camming pin 26, attached toplunger 14, slides. An overhang 30 extends downwardly towards a centerlongitudinal axis of the instrument to provide a stop for the spring 34.Plunger 14 is slidably positioned in the longitudinally extending boreof the elongated body portion 12 and is spring biased proximally to anextended position by spring 34.

In use, in the at rest (undeployed) position shown in FIG. 3 the camplate 24 is positioned entirely within the body portion 12. Uponmovement (depression) of the plunger distally from its extended positionin the direction of the arrow in FIG. 4, camming pin 26 slides distallyalong cam slot 27 to force cam plate 24 upwardly through aperture 18thereby stretching, i.e. expanding, the membrane 16. Upon release ofplunger 14, spring 34 moves from its compressed position of FIG. 4 toits normal position, thereby returning the plunger 14 to its initialposition and allowing cam plate 24 to return to the original position ofFIG. 3.

FIG. 5 illustrates an alternate embodiment of the apparatus of FIG. 1utilizing a slide button 5 which protrudes outwardly from elongatedhandle 3 and slides within slot 4. The slide button 5 is operativelyconnected to a slide rod (or plunger) for moving the cam plate to deploythe membrane. In the alternate embodiment of FIG. 6, a movable handle 7pivots in relation to stationary grip portion 8. Movable handle 7 isoperatively connected to a slide rod (or plunger) for actuating the camplate and expanding the membrane as discussed above with respect to FIG.3. Note that not only these handle mechanisms, but any other mechanismsfor reciprocating a rod, can be utilized with the embodiment of FIGS.1-4 as well as with the alternate mechanisms for deploying the membranewhich are discussed in detail below.

FIGS. 7-9 illustrate an alternate embodiment for expanding membrane 16.

Plunger 40 has an abutment surface 44 adapted to contact lift plate 46to force it upwardly through aperture 18 in elongated body portion 12.As shown, lift plate 46 is pivotally attached to end cap 22 of the bodyportion 12 by pivot pin 48. Upon movement of plunger 40 distally in thedirection of the arrow of FIG. 9, abutment surface 44 cams lift plate 46upwardly through aperture 18; lift plate 46 pivoting around pivot pin 48and compressing spring 50. Distal movement of the plunger 40 alsocompresses spring 42 against overhang 30. Upon release of the plunger40, spring 42 forces the plunger 42 toward its original position andspring 50 causes lift plate 46 to return to its original at restposition of FIG. 7.

In the embodiments of FIGS. 1-9, the pivoting plates extend through asmall aperture in the elongated body portion so that a smaller portionof the membrane is fully extended and the stretching force is appliedagainst a relatively small area of the body tissue. If desired, theinstrument can be advanced or retracted with the membrane deployed tocontinuously stretch the body tissue or alternatively, the membrane canbe repeatedly deployed (expanded) and retracted to intermittentlystretch the body tissue. In FIGS. 10-19, the distal aperture in theelongated member is longer than in FIGS. 1-9 to provide a larger area ofcontact with the membrane. This allows for expansion of a larger portionof the body tissue, and if of sufficient length, can avoid, if desired,the necessity of continuous or intermittent stretching of body tissue byexpanding the entire body structure in a single gradual deployment ofthe membrane.

Turning now in detail to the embodiment of FIGS. 10-12, elongated bodyportion 60 extends from handle 10 and has a longitudinal bore forslidably receiving plunger 62. Elongated aperture 66 and proximalaperture 68 are formed in the body portion and the body portion iscovered by membrane 64. Leaf spring 61 is positioned within the bodyportion and has a distal leg frictionally positioned in recess 69 of endcap 63. The proximal leg is positioned within recess 67 of plunger 62.Upon movement of plunger 62 distally in the direction of the arrow ofFIG. 12, the leaf spring 61 is compressed such that the upper portion isforced outwardly through elongated aperture 66 to stretch (expand)membrane 64. Compression spring 65 biases the plunger to its proximal atrest position in the same manner as discussed with the embodiment ofFIG. 1.

In FIGS. 13-15, elongated body member 70, extending from handle 10, hasend cap 80, and elongated aperture 76 and proximal aperture 78. Plunger72, slidably received in the longitudinal bore of the elongated member70, includes a spring 92 biasing it to the at rest (extended) positionand further has a slot 94 at its distal end to receive pin 84.

Elongated plate 82, preferably in the shape of a parallelogram, has alower portion 83 with longitudinally extending pin 84 extending intoslot 94 of plunger 72. A series of cam plates 86, preferably three asshown in FIG. 13 although additional or fewer cam plates can beutilized, are positioned within elongated member 70. More specifically,plate pin 88 connects the upper end of each cam plate 86 to lowerportion 83 of elongated plate 82 and housing pins 89 connect the lowerend of each cam plate 86 to the inner support 85. (For clarity, only onepin 89 is numbered in FIGS. 13 and 15.) Step 96 of plunger 72 is adaptedto come into contact with stop 91 of inner support 95 to limit movementof plunger 72.

In use, distal movement of plunger 72 forces elongated plate 82 to pivotcounterclockwise as cam plates 86 are rotated to the vertical positionshown in FIG. 15. Longitudinal pin 84 slides to the upper portion ofslot 94 in plunger 72. Elongated plate 82 slides through aperture 86 tostretch membrane 74. Spring 92 operates in a similar manner as discussedabove with respect to FIG. 1 in biasing the plunger proximally.

FIGS. 16 and 17 illustrate an alternate embodiment using a plate 116having cam slots 118 and camning pin 120. Positioned within elongatedbody portion 101 is end cap 110 and spring retaining wall 114, withspring 112 positioned therebetween to bias spring retaining wall 114proximally.

Upon distal movement of plunger 102 in the direction of the arrow ofFIG. 17, cam plate 116 is forced distally and upwardly to the positionshown in FIG. 17 due to angled cam slots 118. This upward movement ofcam plate 116 through aperture 106 stretches membrane 104. This distalmovement of cam plate 116 forces spring retaining wall 114 distallytowards end cap 110 thereby compressing spring 112. Upon release ofplunger 102, spring 126 and spring 112 operate to return the plunger andcam plate 116 to the at rest position of FIG., 16.

In the alternate embodiment of FIGS. 18 and 19, elongated body portion130 includes an upper plate 140 and a lower camming plate 142 positionedbetween end cap 144 and abutting wall 148 of plunger 132. The dovetailfitting of the plates 140 and 142 can be seen in FIG. 18A. Upon distalmovement of plunger 132 in the direction of the arrow of FIG. 19, lowercam plate 142 is slid distally, thereby camming upper plate 140 upwardlythrough the aperture in the elongated body portion to contact and expand(stretch) the membrane 134. Spring 146 biases the plunger to theproximal at rest position in the same manner described upon with theother embodiments. Optionally, a spring can also be provided to biaslower cam plate 142 proximally.

FIGS. 20-23 illustrate an alternative apparatus for expanding a membraneutilizing a slide button mechanism. More specifically, the instrumenthas a elongated grip portion 203, a slot 204 to allow movement of slidebutton 205, an elongated body portion 207 having elongated aperture 215and proximal aperture 217, and a membrane 206.

With reference to FIG. 23, handle 203 includes opposing housing halves203 and 203B, with housing half 203B having an elongated slot 211 toreceive projection 213 of slide button 205.

Elongated body portion 207 has a support member 223, and a spring 219positioned at the distal end portion 214. Support member 223 has arecess 224 to receive spring 219.

Slide plate 209 is positioned within body portion 207 for longitudinalreciprocal movement therein and is biased to a distal position by spring223. Wall 229 of support member 223 acts as a stop for slide plate 209as it is contacted by step 227. Aperture 226 of slide plate 209 receivesprojection 213 of button 205 such that movement of button 205 carriesslide plate 209 in the same direction. Spring 223 is positioned inaperture 228.

In use, in the initial position, retaining wall 225 of slide plate 209is positioned over spring 219 to forceably retain it in the flattenedpositioned of FIG. 21. Upon proximal movement of slide button 205 in thedirection of the arrow in FIG. 22, the slide plate 209 is likewisepulled proximally so that retaining wall 225 is slid rearwardly to freespring 219 to allow it to move to its normal extended position. In thisextended position, spring 219 extends through aperture 215 to stretchmembrane 206. Such movement of slide button 205 to the deployed positioncompresses spring 223 as shown in FIG. 22. Upon release of the slidebutton 205, slide plate 209 is forced distally by spring 223 to itsoriginal position, thereby forcing spring 219 to the position of FIG. 21as it is cammed downwardly by retaining wall 225. Spring 219 can becomposed of memory metal or other materials so that the position of FIG.22 is its normal position and it is constrained by retaining wall plate209.

FIGS. 24-26 illustrate an alternate embodiment of an apparatus fordeploying a spring member utilizing a slide button. More specifically,slide button 255 extends through slot 254 in elongated handle 250 and isconnected to plunger 259 via projection 256. Elongated body portion 257has a distal portion 258, end cap 263 and elongated aperture 251.

Positioned within body portion 257 is a plate 260 having apertures 267and 269. Pad 262, preferably composed of a soft compressible material,is positioned atop plate 260. Pad 262 has flange 264 for contact withwalls 268 and 268' when the spring is deployed. End cap 263 terminatesat its proximal end with a stop 270 to limit distal movement of plunger259.

In use, slide button 255 is slid distally in the direction of the arrowto the position of FIG. 26. This sliding movement of plunger 259 movesplate 260 distally, thereby aligning apertures 267 and 269 with theraised portions of spring 265. As the raised portions project throughthe apertures, they force pad 262 upwardly into contact with themembrane 256 to stretch the membrane. Upward movement of pad 262 islimited by the contact of flange 264 with walls 268, 268'. When plate260 is pulled proximally by slide button 255, the raised portions of thespring 265 are cammed downwardly by plate 260 and then retained by thesolid surface portions of the plate, thereby allowing pad 262 to returnto its at rest position of FIG. 24.

As can be seen, each of these instruments provide mechanical means forexpanding a membrane to expand or stretch a body portion. When used incarpal tunnel surgery, it stretches the transverse carpal ligament toexpand the carpal tunnel, thus relieving pressure on the median nerve.Preferably, the membrane is expandable only upwardly from the centrallongitudinal axis. That is, the spring or substantially rigid cam platepreferably moves in one direction, e.g. away from a central longitudinalaxis, so that the membrane is expandable around less than a 360°peripheral portion of the tubular elongated member. The instruments ofthe present invention can also be utilized for procedures other thancarpal tunnel surgery which require stretching body structures. Theinstruments of the present invention also allow for controlled, andprogressive if desired, stretching of the membrane by the surgeoncontrolling the distance of travel of the reciprocating slide rod.

FIGS. 27-32 illustrate yet other alternate embodiments of the apparatusutilizing a pair of jaws for stretching the body portion. With referencefirst to the embodiment of FIGS. 27-29, instrument 300 has a handle 310,a body portion 312 extending therefrom and a plunger of 314 positionedfor longitudinal reciprocal movement therein. A pair of jaws 316, 318are connected to drive rod 320 which extends distally from cutout 330 ofplunger 314. Upon distal movement of plunger 314 in the direction of thearrow of FIG. 29, drive rod 320 is moved distally, thus allowing cammingpin 324 to travel in angled cam slots 322 forcing the jaws to pivotaround pivot pin 326 to the open position. Spring 328 biases the plungerproximally to the at rest position of FIG. 27. Alternatively, the jawscan be configured so that one of the jaws is stationary and only one ofthe jaws is movable. A membrane can optionally be placed around thejaws.

In the alternate embodiment of FIGS. 30-32, the jaws are containedwholly within the elongated body portion until deployed. As shown, bodyportion 352 extends from handle 350 and has a longitudinal bore toreceive plunger 354 for reciprocal movement therein. Drive rod 360 ispositioned within cutout 372 of plunger 370. Upon distal movement ofplunger 354 in the direction of the arrow of FIG. 32, the drive rod 360carries camming pin 364 distally in angled cam slots 362 to open thejaws as shown in FIG. 32 as they pivot around pivot pin 366. Thisstretches the membrane 355. Spring 370 functions in the manner asdescribed above with respect to FIG. 27 in biasing the plungerproximally.

While the invention has been particularly shown and described withreference to the preferred embodiments, it will be understood by thoseskilled in the art that various modifications in form and detail may bemade therein without departing from the scope and spirit of theinvention. Accordingly, modifications such as those suggested above, butnot limited thereto, are to be considered within the scope of theinvention.

What is claimed is:
 1. A method for expanding the carpal tunnel ligamentduring carpal tunnel surgery comprising:a) providing an instrumenthaving a spring member positioned therein; b) inserting the instrumentinto the carpal tunnel; c) extending the spring member to protrude fromthe instrument to stretch the carpal tunnel ligament; d) retracting thespring member; and f) withdrawing the instrument from the carpal tunnel.2. The method of claim 1, wherein the steps (c) and (d) are repeated aplurality of times such that the rigid member repeatedly moves in thefirst and second direction to stretch the carpal tunnel ligament.
 3. Themethod of claim 2, wherein the step of actuating the moveable memberincludes actuating a handle member operatively connected to the moveablemember.
 4. The method of claim 2, wherein the step of actuating themoveable member includes actuating a slide member operatively connectedto the moveable member.
 5. The method of claim 2, wherein the step ofactuating the moveable member includes actuating a plunger memberoperatively connected to the rigid member.
 6. An apparatus for expandingthe carpel tunnel ligament during carpal tunnel surgery, whichcomprises:a) an elongated body portion having an outer wall surface andat least one aperture extending through the outer wall surface, the bodyportion defining a longitudinal axis and having proximal and distalends; b) at least one substantially rigid member adjacent the distal endof the body portion, the one rigid member movable between a firstposition, at least partially contained interiorly within the outer wallsurface of the body portion and a second position protruding outwardlythrough the aperture in the outer wall surface of the body portion, therigid member having an engaging surface dimensioned and configured toengage and stretch body tissue upon movement of the one rigid member tothe second position thereof; and c) a deployment member at leastpartially extending through the body portion and operatively engageablewith the rigid member, the deployment member adapted for movementrelative to the elongated body portion to cause the one rigid member tocorrespondingly move between the first and second positions.
 7. Theapparatus of claim 6, wherein the deployment member includes a plunger.8. The apparatus of claim 6, further including a handle member connectedto the body portion, the handle member including a frame and a manuallyactuable member mounted to the frame and movable relative thereto, themanually actuable member operatively connected to the deployment memberwherein movement of the actuable member moves the deployment member tocause corresponding movement of the rigid member between the first andsecond positions thereof.
 9. An apparatus for expanding the carpeltunnel ligament during carpal tunnel surgery, which comprises:a) anelongated body portion having an outer surface and at least one aperturein the outer surface, the body portion defining a longitudinal axis andhaving proximal and distal ends: b) at least one substantially rigidmember adjacent the distal end of the body portion, the one rigid membermovable between a first position at least partially contained interiorlywithin the outer surface of the body portion and a second positionprotruding outwardly through the aperture in the outer surface of thebody portion, the rigid member having an engaging surface dimensionedand configured to engage and stretch body tissue upon movement of theone rigid member to the second position thereof; c) a deployment memberat least partially extending through the body portion and operativelyengageable with the rigid member, the deployment member adapted formovement relative to the elongated body portion to cause the one rigidmember to correspondingly move between the first and second positions;and d) camming structure associated with each of the one rigid memberand the deployment member, wherein movement of the deployment member inone longitudinal direction causes the one rigid member to move from thefirst position to the second position through cooperative interaction ofthe respective camming structure.
 10. An apparatus for expanding thecarpel tunnel ligament during carpal tunnel surgery, which comprises:a)an elongated body portion having an outer surface and at least oneaperture in the outer surface, the body portion defining a longitudinalaxis and having proximal and distal ends; b) at least one substantiallyrigid member adjacent the distal end of the body portion, the one rigidmember movable between a first position at least partially containedinteriorly within the outer surface of the body portion and a secondposition protruding outwardly through the aperture in the outer surfaceof the body portion, the rigid member having an engaging surfacedimensioned and configured to engage and stretch body tissue uponmovement of the one rigid member to the second position thereof; c) adeployment member at least partially extending through the body portionand operatively engageable with the rigid member, the deployment memberadapted for movement relative to the elongated body portion to cause theone rigid member to correspondingly move between the first and secondpositions; and d) a handle member connected to the body portion, thehandle member including a frame and a manually actuable pivotable memberpivotally mounted to the frame and operatively connected to thedeployment member, the pivotable member adapted for pivotable movementto move the deployment member in a general longitudinal direction tothereby cause corresponding movement of the one rigid member between thefirst and second positions.
 11. An apparatus for expanding the carpeltunnel ligament during carpal tunnel surgery, which comprises:a) anelongated body portion having an outer surface and at least one aperturein the outer surface, the body portion defining a longitudinal axis andhaving proximal and distal ends; b) at least one substantially rigidmember adjacent the distal end of the body portion, the one rigid membermovable between a first position, at least partially containedinteriorly within the outer surface of the body portion and a secondposition protruding outwardly through the aperture and the outer surfaceof the body portion, the rigid member having an engaging surfacedimensioned and configured to engage and stretch body tissue uponmovement of the one rigid member to the second position thereof; c) adeployment member at least partially extending through the body portionand operatively engageable with the rigid member, the deployment memberadapted for movement relative to the elongated body portion to cause theone rigid member to correspondingly move between the first and secondpositions; and d) a handle member connected to the body portion, thehandle member including a frame and a manually actuable slide buttonslidably mounted to the frame and operatively connected to thedeployment member, the slide button adapted for longitudinal movement tomove the deployment member in a general longitudinal direction tothereby cause corresponding movement of the one rigid member between thefirst and second positions.
 12. An apparatus for expanding the carpeltunnel ligament during carpal tunnel surgery, which comprises:a) anelongated body portion having an outer surface and at least one aperturein the outer surface, the body portion defining a longitudinal axis andhaving proximal and distal ends; b) at least one substantially rigidmember adjacent the distal end of the body portion, the one rigid membermovable between a first position at least partially contained interiorlywithin the outer surface of the body portion and a second positionprotruding outwardly through the aperture in the outer surface of thebody portion, the rigid member having an engaging surface dimensionedand configured to engage and stretch body tissue upon movement of theone rigid member to the second position thereof; c) a deployment memberat least partially extending through the body portion and operativelyengageable with the rigid member, the deployment member adapted formovement relative to the elongated body portion to cause the one rigidmember to correspondingly move between the first and second positions;and d) a spring member dimensioned for biasing the deployment member toa position corresponding to the second position of the one rigid member.